4 zones is enough for a 10" and will make testing your first mirror easier.
I forgot... typical printer card stock is 8 1/2 x 11"... doesn't have to be 10" each way. So the mask can be printed on one sheet.
Here is what the Couder Mask 4 zone looks like, with some data printed on it for convenience, and central area behind the secondary grayed out just so you know what I'm saying about the shadow.
The very center is difficult to measure accurately, but it is behind the secondary, so there is an area of the mirror just a little smaller than the secondary that is not used. No need to measure that. With the secondary shadow in mind, I chose a convienient inner radius for the first zone that helped to make all target knife movements zone to zone to be the same.
The outer radii of the outer zone is just a little smaller than the full mirror radius to account for a bevel and leave out some of a possible turned edge that might cause difficulty finding a null for the outer zone.
The Couder Mask program numbers the first zone as 0. I have renumbered to have the first zone as zone 1.
5 zones is ok, and I have dimensions for a good 5 zone Couder screen too. :-)
Mirror diameter 254 mm
Clear aperture 250 mm
Zone R inner R outer R center
1 17.750 57.000 39.868
2 57.000 79.000 68.443
3 79.000 97.000 88.230
4 97.000 111.250 104.247
5 111.250 125.000 118.225
For 10" f:6 0.02" (0.508 mm) knife movement between each zone.
Pinstick method might work ok. I've done that before but came to like using a mask.
I'll let others work with you on that. It's been more than a few years since I have done the pinstick thing.
See with the 4 zone mask in testing you get 4 zone reading.
There are 3 knife movements between those zones.
It is the knife movement that you want to know.
Assuming a moving source tester (light source and knife move together:
If zone 1 knife movement is nearest the mirror and knife 0.025" farther away from the mirror for each zone outward, the mirror is near perfect.
It is somewhat difficult to get all three movements perfect. Get them as close as possible to the target.
If tester's light source is fixed knife movements would .05" between adjacent zones.
I have one comment (at least) on tester design. The Stellafane tester does not account for your nose. If you look at there tester design, you can have the knife and light source without the big "face board". Modern LED's are small and a knife and light source unit can be small and mounted on a suitably shaped support so you can get your eye to it without touching it with any part of you face. :-) You should consider which eye you prefer to use for testing. if you are left eyed you may want the knife and light source to the right side of the base.
I think it is safe to say you will have to build and use a tester to learn how you should have made it in the first place. :-)
A skilled tester can do pretty well with a junk tester. A beginner will have much trouble with anything less than the best.
But it is not likely you will have the best, and it's part of learning, to manage with less than the best.
Don't let that worry you. A 10" f:6 is not really all that difficult. You should be able to do pretty well with a typical Mark 1 Foucault tester.
Perhaps a test tunnel of some sort can be fabricated to block drafts.
My first mirror was a 10" f:6. Great views with that mirror.
You have a good sphere and edge, so time to parabolize.
Try 5 turns of MOT parabolizing strokes like this one.
This is a not the typical full size parabolizing stroke.
It's a little smaller so that hopefully the central crater that most beginners get with the larger size stroke will be avoided.
See how this one works and maybe later a larger one will be used.
It is mostly the overhang to left and right that add the correction. It is added at the left and edges of the lap.
So it is the central parts of the W that add correction to the outer zone of the mirror and outer parts of the W that add correction to the mirror's center.
Pressure increases quickly with added overhang so the center tends to correct faster than the outer zone.
The forward and back overhang adds some but not as much as left and right overhang.
Notice on the left and right ends of the stroke the stroke direction has an increased lateral component. This reduces the tendency of developing a central dimple or trenches near center. Some of this would be in the secondary mirror shadow, but as a matter of pride you don't want this ugly stuff.
5 turns should be enough to see some movement toward the parabola and not enough work to make a big mess if it doesn't go right.
Do it like the drawing, starting on one side of the W, stroke to the other side, turn the mirror about 1/12 turn and take a similar size (give or take a little) around the barrel. I go around the same way I turn the top disk, but I don't think it matters much. Stroke the W back across the other way, turn, step, across the other way and so on. Concentrate on doing it the same every time as you make the full turn of the mirror.
A 10" mirror is a nice size for fit to hands. A good method is to place hands palm down with thumb tips touching at the center of the mirror. Slight dampness of the hands will help grip the glass. Downward pressure is evenly distributed over all of palm and finger contact with the glass. You don't need to apply much pressure to get a grip for stroking. I'd say about 10 or 12 pounds total.
Don't change that even distribution. The stroke diagram shows the path of the mirrors center over the lap. Use you thumb tips as a marker of the mirrors center. You could place a small piece of tape there too if you like. The mirror will not tip over the edge of the lap as long as the center of the mirror doesn't go past the edge. So even though you will be using where the center gets near the edge, you will not go past the edge, don't worry about it.
If it takes about 2 seconds for each stroke (forward and back = 1 stroke), the 5 stroke across the W will take 10 seconds. 12 times of that for a full turn of the mirror will be about 120 seconds or 2 minutes. 5 turns about 10 minutes for the entire work session. Do only 5 turns. Time it and let me know how long it actually takes you to do those 5 turns. Don't do more.
Test and lets see what happened. When the result is seen maybe something else would be better.
There is a tendency to want to work more in one session. It can lead to trouble and much back tracking. Small steps to the parabola.